A fully functional evaluation copy can be downloaded from our web site. The downloaded product will run in evaluation mode for a period of 30 days. If you want to continue to use the product after this period, you're required purchase a license.
Download a 30-days trial now

Yes, we do permit a single authorized end user to make a second copy for end user's exclusive use on a second computer as long as only one (1) copy of the purchased software is in use at any one (1) time. No other end user may use the software under the same license at the same time for any other purpose.

Please take a look at the Converting RS-274D Gerber files to extended Gerber format tutorial.

You will find an article online that describes how you can use GerbView to combine positive and negative layers into a single Gerber file.

You will find a description of all available command line parameters here.